[processing] Some History dialog UX fixes:

- fix tiny folder icon on hidpi
- remember window geometry

Author: nyalldawson

python/plugins/processing/gui/HistoryDialog.py

@@ -28,6 +28,7 @@
 import os
 import warnings
 
+from qgis.gui import QgsGui
 from qgis.PyQt import uic
 from qgis.PyQt.QtCore import Qt, QCoreApplication
 from qgis.PyQt.QtWidgets import QAction, QPushButton, QDialogButtonBox, QStyle, QMessageBox, QFileDialog, QMenu, QTreeWidgetItem
@@ -49,11 +50,10 @@ def __init__(self):
         super(HistoryDialog, self).__init__(None)
         self.setupUi(self)
 
-        self.groupIcon = QIcon()
-        self.groupIcon.addPixmap(self.style().standardPixmap(
-            QStyle.SP_DirClosedIcon), QIcon.Normal, QIcon.Off)
-        self.groupIcon.addPixmap(self.style().standardPixmap(
-            QStyle.SP_DirOpenIcon), QIcon.Normal, QIcon.On)
+        QgsGui.instance().enableAutoGeometryRestore(self)
+
+        self.groupIcon = self.style().standardIcon(
+            QStyle.SP_DirClosedIcon)
 
         self.keyIcon = self.style().standardIcon(QStyle.SP_FileIcon)